Caffeine makes you feel like rat’s piss though, as it dehydrates you. Otherwise it’s great.
People get hangovers from weed because their gear was mixed with either fertilising chemicals or substances like wax or even plastic. How does a painkiller get rid of the chemicals?

Yep painkillers work fine, but for many just combine the effect of a groggy weed hangover with it. Also, when the effect wears off, your headache kicks back in. At least try to avoid relying on them and flush out your toxic crap instead.

Cleaning your weed? I don’t know where that came from. Get homegrown if you are unsure. Free of evil dealer crap. Like drinking alcohol with no impurities, homegrown is organic and hangover free.
There are tiny, tiny bits of glass in some weed. As for wax it is often mixed with hash. If you don’t believe me then burn your brown chuff and watch it closely. If it bubbles slightly, then wax is in there.

It’s all about hydration. Alcohol in large qutiiatnes can lead to dehydration. The best way to have a hangover . other than avoiding alcohol . to avoid is to try to drink a glass of water to every 2-3 drinks alcohol. Keep yourself hydrated if you can then avoid a hangover. Hope this helps.